When using rapid dry methods for aggregate, which practice helps prevent localized overheating and aggregate fracturing?

• A. Stir the sample frequently to prevent localized overheating and aggregate fracturing.
• B. Do not stir; keep energy constant.
• C. Increase temperature to maximum.
• D. Use larger samples.

Answer: (A)

Even heating is essential in rapid dry methods, and stirring the sample helps distribute heat so no small portion gets much hotter than the rest. Localized overheating creates thermal stress in the brittle aggregate, leading to microscopic cracks or fracturing that skew results and weaken the sample. By stirring frequently, heat and moisture removal are more uniform throughout the batch, reducing temperature gradients and the risk of hot spots. The alternative of not stirring allows hotspots to form, keeping energy constant without addressing uneven heating, increasing the chance of damage. Pushing temperature to the maximum or using larger samples likewise makes it harder to achieve uniform drying and can enhance thermal stress and fracturing. In short, regular stirring promotes even drying and protects the integrity of the aggregate.